Tungsten-reducing furnace.



C. A. PFANSTIEHL.

TUNGSTEN REDUCING FuRNAcE.

APPLICATION FILED APR.26. 2915.

Patented Dec. 31, 1918.

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UNITED sTATEs PATENT orrucn.A

CARL A. PFANSTIEHL, OF WAUKEGAN, ILLINOIS,l ASSIGNOR T0 PFANSTIEHL COMPANY,y

INC., OF NORTH CHICAGO, ILLINOIS, .AI CORPORATION OF NEW YORK. l

TUNGsTN-BEDCING FURNACE.

' 'Be it known that I, CARL A. PFANSTIEHL, a citizen of the United States, residing at Waukegan, in the countyv of Lakeand State of Illinois, have invented certain new and useful Improvements in Tungsten-Reducing Furnaces, of Iwhich lthe following is a clear, concise, and exact description, reference be ing had to the accompanying drawings,

' forming a part of this specificatlon.

My invention relates to tungsten reducing furnaces of the character adapted for use 1ncommercial purposes.

lIn 'the manufacture of malleableI and ningot is heated to weld the particles together.

I have found that very fine tungsten powder may be secured by. the reduction of very finely divided tungsten trioxid in a suitable reducin furnace. I 'have found also that too rapid heating of the tungsten trioxid, even in the presence of a large excess of hydrogen, causes crystallization of the re'- duced tungsten and causesthe particles instead of being individually reduced to adhere to one another in the form of coarse and more or less crystalline powder. While it is possible to produce ductile tungsten from such coarse tungsten powder it must be treated in a manner much more expensive than. the manner which I use in producing ductiletungsten from the very finely divided.

tungsten powder which may be produced by the apparatus herein described.

The apparatus of my present invention provides meansfor initially 'heating the tungsten trioxid in an atmosphere of hydrogen Vwhich is somewhat rapidly circulated over the tungsten trioxid. in order to lcarry oif the moisture formed by the union of the l hydrogen and oxygen, the presence of water vapor also being detrimental to the formation o f nely divided tungsten. It has been customary in the past to Vslowly heat the tungsten' trioxidby bringing up the temperature 'of the reducing furnace very gradspeeication of Letters Patent.' `Patented Dec. 31, 1918.

Application led April 26, 1915. Serial No. 24,038.

operation. At the end of the reducing op-v eratlon the furnace must then be cooled down before a'second charge of tungsten trioxid may be lnserted. My present insvention embraces an electrically heated furnace of the tubular type, having extensions therefromv at each end 0f the tube into one of which carriers or boats containing tungsten trioxid may be fed, and from the other of which these boats containing pure tungsten powder may -b'e removed, ,means bein provided for slowly drawing -theboats yo tungsten trioxid through the furnace so that the temperature of the tungstentrioxid is raised very gradually and the tungsten itself is cooled without the necessity of cooling down the reducing furnace between. charges. 1

My invention is illustrated in the accompanying drawing in which,

Figure l illustrates the furnace with its charging and discharging tubes extending therefrom. v

Fig. ,2 is a section through the furnace 8o with the charging and discharging tubes broken away.

Fig. 3 is a sectlon through the plug at i Like parts arerepresented by the same figures throughout all of the views.

The furnace proper comprises a main inclosing tube of metal 10,- having circular metallic ends 11 and 12', which, .when taken with the tube 10, forma box or retainer for the silica, or other refractory substance 13. Extending through this lbox and substantially four feet beyond the right end thereof is a metallic or silica tube 15 around which,

within'the box and embedded in the refractory material 13, are two resistance coils 16 and 17. These coils are somewhat larger 4'than the tube 15 and areheld by the refrac-4 tory material so that they do not come into electrical connection with the` tube 15. The coil 16 is provided with terminals 18 and 19, and the coil 17 with terminals 20 and 21 which are electrically separated from the tube 10 by insulating bushings 22. These coil terminals are connected with a suitable source of electricity, that for the coil 16 being diagrammatically illustrated as agenerator 25, and that for coil 17 being diagrammatically illustrated as a generator 26.

The tube 15 extends only a slight distance beyond the end of the furnace box at .vhich point it joins a second tube vof similar diam `eter 27, the junction point being embracedby a cooling jacket 28 through which Water or other cooling fluid is circulated. The

right hand end of the tube 15, as abovek stated, extends about four feet'beyond the furnace box and is also embraced at itsend by a cooling jacket 29 through which cooling liquid is circulated. The Ileft hand end. of the tube 27 is provided with a snugly fitting plug 30 through which the hydrogen intake tube 31 is 'itted, the plug 30 also being provided with an opening through which a nickel or tungsten wire 32 iits somewhat closely. The plug 30 is preferably of some soft material such as cork or rubber so thatthe opening through which the wire 30l passes will be substantially gas tight, though permitting the wire to be drawn through it.

The boats or carriers 35,- shown in perspective in Fig. 4, are preferably -In'adeof pure the left hand end of the furnace is maintained at a high temperature whilethe right ha'nd end thereof is maintainedv at a. lower temperature. In order to char e the furnace before a reducing run the p ugs 30 and 37 are removed and a train of boats 35 charged with tungsten trioXid, and having attached to it a wire 32 long enough to reach through the entire furnace is threaded in from the right hand end, the projecting end of the wire 32 being threaded through the opening in the stopper 30, passed over the pulley 38, and attached to the mechanically operated drawing pulley 39. The plugs 30 and 37 are then placed in the ends of the tubes 27 and 15 and the hydrogen supply is turned' on and allowed to pass through the. tube from left to right until all of. the air has been driven out. The mechanically operated drawing mechanism 39 is then started and the boats containing the tungsten trioxid are slowly drawn through the furnace.

Hydrogen gas is itself a good carrier of heat and since it is circulating from left to right it becomes heated as it passes through the heating coils 16 and 17 and gradually brings up the temperature of the boats or carriers and the tungsten trioXid contained therein. It requires from four to eight hours to complete the reduction of one charge of tungsten, but as soon as this charge has passed through the furnace and assumed its position in the tube 27, which is kept at a low temperature by the Water jacket 28 and the presence of fresh cool hydrogen, the boats and their contents may be removed and others immediately inserted Without Waiting for the furnace to cool, and, in fact., without even interrupting the electric circuits through the heating coils. Y j

My invention, therefore, provides meansl for producing very fine tungsten powder satisfactory for manufacturing malleable and ductile tungsten in less time than it has been heretofore possible to perform this operation and with practically no loss of time between the furnace charges. -Although I have shown and described my invention with respect to details illustrated in the drawings, I do not wish -to be unduly limited thereto, it being obvious that many modifications may be made without departing from the spirit or scope of my invention.

f What I claim and wishto secure by Letters Patent is:-

1. A reducing furnace for tungsten trioXid comprising a-comparatively long and slender metallic tube, a pair of heating elements surrounding different portions of said tube, refractory material in which said heating elements are embedded, and 'means to independently control the current supplied 100 to said heating elements so as to control theheating efl'ects thereof and means to draw the tungsten trioxid from the zone of effect of one heating element into the zone of effect of the other. 4

2. A reducing furnace for tungsten trioxid comprising a tube, heating elements located near one end of said tube and adapted to heat the same, a cooling jacket for the eX- treme end of said tube, a second tube reg- 110 istering with the first within 'said cooling jacket, hydrogen injection means connected with the second tube, hydrogen exhaust means connected with the rst tube, carriers, and means to draw said carriers through the 11 5 heated portion of the first tube into the second tube.

3. In a reducing furnace, a long and slender tube, means for admitting reducing Huid at one end and discharging it at the other 120 end of said tube, said tube comprising a charging chamber at the iuid ejection end heated by the hot fluid, a second chamber adjacent thereto, an electric heating element surrounding said second chamber, a third chamber adjacent thereto, a second and independent electric heating element surrounding said third chamber, a cooling element adjacent to the last named chamber, a cooling chamber at the fluid admission end 130 of the tube and means for drawing the material to be reduced from the charging chamber to said last named chamber.

4. A reducing furnace for tungsten trioXid comprisin a long and slender tube, one end of sai tube forming a charging chamber into which tungsten trioXid to be reduced is admitted, the central portion of said tube having a chamber in which the tungsten trioxid is heated and reduced to metallic tungsten, a resistance element for heating the latter portion of said tube, and the other end of said tube having a cooling charging chamber through the reducing chamber and into the cooling chamber.

In Witness whereof, I hereunto subscribe 20wy my name this 21st day of` April, A. D.'1915.

CARL A. PFANSTIEHL.

Witnesses:

S.u LEPKE, J. W. LEODE. 

